JP2006147345A - Electrode catalyst layer and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of preventing time-lapse outflow of platinum from an electrode catalyst layer, in a polymer electrolyte fuel cell. <P>SOLUTION: This electrode catalyst layer for a polymer electrolyte fuel cell contains a conductive catalyst support, a catalyst active material supported to the conductive catalyst support and containing platinum, and a proton conductive polymer. A platinum capture agent capable of capturing platinum ions is further included in the electrode catalyst layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polymer electrolyte fuel cell. More specifically, the present invention relates to an electrode catalyst layer in a polymer electrolyte fuel cell.

  A fuel cell is a clean power generation system in which the product of an electrode reaction is water in principle and has almost no adverse effect on the global environment. Various fuel cells such as a polymer electrolyte fuel cell, a solid oxide fuel cell, a molten carbonate fuel cell, and a phosphoric acid fuel cell have been proposed as fuel cells. Among these, a polymer electrolyte fuel cell (PEFC) can be operated at a relatively low temperature, and thus is expected as a power source for moving bodies such as automobiles, and is being developed.

  The polymer electrolyte fuel cell includes a proton conductive solid polymer electrolyte membrane and a pair of electrodes that sandwich the solid polymer electrolyte membrane. One electrode is an anode (oxygen electrode) supplied with an oxidant, and the other electrode is a cathode (fuel electrode) supplied with hydrogen gas.

  FIG. 1 is a schematic view of an embodiment of a solid polymer fuel cell. As shown in the figure, a polymer electrolyte fuel cell 10 includes a membrane electrode assembly (MEA) 100 and a membrane electrode assembly 100 disposed so as to sandwich the membrane electrode assembly 100 outside the membrane electrode assembly. And a pair of separators 200. A current collector 300 is disposed outside the separator 200. The membrane electrode assembly 100 includes a proton conductive solid polymer electrolyte membrane 110, a pair of electrode catalyst layers 120 arranged so as to sandwich the solid polymer electrolyte membrane 110, the polymer electrolyte membrane 110, and an electrode catalyst. It is a laminate having a pair of gas diffusion layers 130 arranged so as to sandwich the layer 120. A carbon layer 140 or the like can be stacked as necessary.

  A gas flow path 210 is formed on the surface of the pair of separators 200 that sandwich the membrane electrode assembly 100 in contact with the gas diffusion layer 130. An oxidant such as air or oxygen gas is supplied to the gas flow path 210 on the anode (oxygen electrode) side. On the other hand, a fuel gas such as hydrogen gas is supplied to the gas flow path 210 on the cathode (fuel electrode) side. The reaction gas supplied to the gas flow path 210 reaches the electrode catalyst layer 120 through the porous gas diffusion layer 130 and the carbon layer 140, and the following chemical reaction formulas (1) and (2):

Electrons are generated by the electrochemical reaction shown in FIG. The electrons are taken out to an external circuit through the current collector 300 and used as electric energy.

  The electrode reaction in the polymer electrolyte fuel cell proceeds in the electrode catalyst layer 120. The electrode catalyst layer 120 contains a noble metal atom such as a platinum atom as a catalyst active material for promoting the progress of the electrode reaction. This catalyst active material is mainly contained in the electrode catalyst layer 120 in a form supported on a conductive carrier such as a carbon carrier. In addition, in order to ensure proton conductivity in the electrode catalyst layer 120, a proton conductive polymer is usually added to the electrode catalyst layer 120.

  Here, when the polymer electrolyte fuel cell including the electrode catalyst layer 120 containing platinum as a catalyst active material is operated for a long period of time, platinum contained in the electrode catalyst layer 120 (particularly, the cathode) is eluted from the conductive carrier. As a result, the solid polymer electrolyte membrane side or the gas diffusion layer side flows out over time, and the catalytic activity of the electrode catalyst layer 120 decreases accordingly.

  Conventionally, as a technique for preventing platinum from flowing out of an electrode catalyst layer of a phosphoric acid fuel cell, a technique in which platinum ions are added in advance to phosphoric acid as an electrolyte in a phosphoric acid fuel cell has been proposed. (For example, refer to Patent Document 1). In this technology, platinum ions are added to the electrolyte phosphoric acid, and the platinum ion concentration in the electrolyte is set to an equilibrium concentration in advance, thereby suppressing the elution of platinum from the conductive support in a noble potential environment. It is.

On the other hand, as a technique for dispersing platinum in a solid polymer electrolyte membrane of a polymer electrolyte fuel cell, a technology for obtaining a self-humidifying membrane has been proposed (see, for example, Non-Patent Documents 1 to 3). ).
JP-A-1-315594 M.M. Watanabe et al., J. MoI. Electroanal. Chem. , 399, 239-241 (1996). M.M. Watanabe et al., J. MoI. Electrochem. Soc. , 145, No. 4, 1137-1141 (1998) M.M. Watanabe et al., J. MoI. Phys. Chem. B, 102, no. 17, 3129-3137 (1998)

  However, such a form may cause a problem in the strength of the electrolyte membrane. Depending on the operating conditions, oxygen and hydrogen that have crossed over may react with the catalytic action of platinum added to the electrolyte membrane to generate hydrogen peroxide, which may cause deterioration of the membrane.

  Therefore, in a polymer electrolyte fuel cell, it is difficult at present to achieve stable operation by adding platinum to an electrolyte membrane and dispersing it, and there is a development of a technology that can replace the technology described in the above literature. What is desired is the current situation.

  Accordingly, an object of the present invention is to provide means capable of preventing platinum from flowing out of the electrode catalyst layer over time in a polymer electrolyte fuel cell.

  The present invention relates to an electrode catalyst layer for a polymer electrolyte fuel cell comprising a conductive carrier, a catalytic active material containing platinum, and a proton conductive polymer, which is supported on the conductive carrier, and comprises platinum ions It is an electrode catalyst layer for a polymer electrolyte fuel cell, further comprising a platinum ion scavenger capable of trapping.

  According to the present invention, it is possible to prevent the platinum from flowing out of the electrode catalyst layer of the solid polymer fuel cell with the lapse of time, and to suppress a decrease in catalyst activity. As a result, a polymer electrolyte fuel cell having excellent durability is provided.

  In the polymer electrolyte fuel cell, electric power is generated by the reaction at the cathode (oxygen electrode) and the anode (fuel electrode) described above. In this case, protons generated around the catalyst active material present in the electrode catalyst layer on the anode side reach the solid polymer electrolyte membrane via the proton conductive polymer dispersed in the electrode catalyst layer, Furthermore, it passes through the solid polymer electrolyte membrane and moves to the cathode side. After that, the proton conductive polymer dispersed in the electrode catalyst layer on the cathode side reaches the catalyst active material on the cathode side, and reacts with oxygen gas and electrons that have passed through the external circuit to generate water. .

  Here, when the activated polymer electrolyte fuel cell is stopped and then operated again, if air is present in the anode in addition to the fuel gas such as hydrogen gas, the anode is filled with hydrogen. Although the normal reaction represented by the chemical reaction formula (2) proceeds, the cathode reaction represented by the chemical reaction formula (1) is not performed on the surface that is not filled with hydrogen and air remains. It will progress.

  Thus, when the cathode reaction proceeds at the anode, the pH in the solid polymer electrolyte varies. As a result, in the electrode catalyst layer, the following chemical reaction formula (3):

As a result of the reaction, platinum is eluted from the conductive support in the form of ions, and finally flows out to the solid polymer electrolyte membrane side or the gas diffusion layer side. As a result, the catalytic activity decreases. Such platinum elution is more remarkable at the cathode.

  As described above, when the start and stop of the polymer electrolyte fuel cell is repeated, the catalytic activity decreases due to the outflow of platinum from the electrode catalyst layer. Therefore, it is preferable to take measures for preventing the outflow of platinum from the electrode catalyst layer in the polymer electrolyte fuel cell.

  In the present invention, by adding a substance capable of trapping platinum ions to the electrode catalyst layer, platinum is prevented from flowing out of the electrode catalyst layer, and a decrease in catalyst activity is suppressed. Specifically, the present invention relates to an electrode catalyst layer for a solid polymer fuel cell comprising a conductive carrier, a catalytic active material containing platinum supported on the conductive carrier, and a proton conductive polymer. A solid polymer fuel cell electrode catalyst layer further comprising a platinum ion scavenger capable of capturing platinum ions.

  Hereinafter, the configuration of the electrode catalyst layer of the present invention will be described in detail.

  The conductive carrier is a substance having a role of supporting a catalytic active material and having conductivity so that electrons can move. The conductive carrier is not particularly limited as long as it can carry a catalyst active material. The conductive carrier actually used can be determined in consideration of the characteristics of the catalyst carrier and the compatibility with the catalyst active material. Specific examples of the conductive carrier include carbon blacks such as acetylene black, carbon materials such as activated carbon and graphite, and various metals. However, other conductive carriers may be used.

  The particle size of the conductive carrier is not particularly limited, but is preferably 10 to 200 nm, more preferably 20 to 100 nm. When the particle size of the conductive carrier is too small, the conductive carrier may be corroded and deteriorated, and the catalyst active material supported on the carrier may fall off with time.

The specific surface area of the conductive support is not particularly limited, preferably 50 to 200 m ² / g, more preferably 100-150 ² / g. If the specific surface area of the conductive support is too small, the dispersibility of the catalyst active material and the proton conductive polymer on the conductive support may decrease, and sufficient battery performance may not be exhibited. Further, if the specific surface area of the conductive support is too large, the effective utilization rate of the catalyst active material and the proton conductive polymer may be reduced, and sufficient battery performance may not be exhibited.

The amount of the catalyst active material supported on the conductive support is not particularly limited, but is preferably 0.7 to 2.0 mg / cm ² , more preferably 0.8 to 1.0 mg / cm ² . If the supported amount of the catalyst active material is too small, the catalyst function may not be sufficiently exhibited. On the other hand, if the amount of the catalyst active material supported is too large, there may be no particular problem from the viewpoint of the catalyst function. However, even if more catalyst active material is supported, an effect commensurate with the increase in production cost is obtained. It becomes difficult to obtain.

  The catalytic active material is a material having a function of promoting an electrode reaction at the cathode or the anode. In the electrode catalyst layer of the present invention, the catalyst active material contains platinum as an essential component. Platinum is superior in catalytic activity compared to other metals.

  The catalyst active material may contain other metals in addition to platinum. The other metal is not particularly limited as long as it has a function of promoting an electrode reaction in the arranged electrode. Specific examples of metals contained in the catalyst active material in addition to platinum include ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, etc. And the alloys thereof. Other metals may be contained in the catalyst active material.

  The particle size of the catalyst active material is not particularly limited, but is preferably 3 to 50 nm, and more preferably 5 to 20 nm. From the viewpoint of improving the catalyst utilization rate, the smaller the particle size, the better. However, when the particle size is too small, it becomes difficult to produce the catalyst active material.

  The proton conductive polymer means a polymer having the ability to move protons. The proton conductive polymer plays a role of transmitting protons generated around the catalyst active material on the anode side. As the proton conductive polymer, a polymer having the same configuration as the polymer constituting the solid polymer electrolyte membrane can be used. For example, perfluorocarbon sulfonic acid polymer, polystyrene sulfonic acid, polytrifluorostyrene sulfonic acid, or the like can be used as the proton conductive polymer.

  The ion exchange capacity (EW) of the proton conducting polymer is not particularly limited, and is usually about 0.9 to 1.1 g / meq, preferably 0.95 to 1.0 g / meq. “EW” shown here represents the equivalent mass of the exchange group having proton conductivity. This mass is the dry mass of the ion exchange membrane per equivalent of ion exchange groups, and is expressed in units of g / meq. If the ion exchange capacity of the proton conducting polymer is too small, the hydrophilicity of the electrode catalyst layer is increased, and there is a possibility that the generated water cannot be smoothly moved. On the other hand, if the ion exchange capacity of the proton conducting polymer is too large, the proton conductivity is lowered and it becomes difficult to obtain sufficient battery performance. However, the technical scope of the present invention is not limited to the above range.

  The electrode catalyst layer of the present invention is characterized in that it further contains a platinum ion scavenger. The platinum ion scavenger means a material having a function of capturing the platinum ion by contact with the platinum ion. By including such a platinum ion scavenger in the electrode catalyst layer, elution of platinum ions from the electrode catalyst layer can be prevented, and a decrease in catalyst activity can be suppressed.

  The platinum ion trapping agent may be a substance having a function of trapping platinum ions, and its specific form is not particularly limited. For example, it is preferable to use a compound capable of forming an organic platinum complex by capturing platinum ions as the platinum ion capturing agent. In such a form, the organoplatinum complex produced by capturing platinum ions can function as an electrode catalyst. That is, reuse of platinum as a catalyst active material is achieved. As a result, it is possible to effectively contribute to extending the life of the electrode catalyst layer.

  The organometallic complex produced by the platinum ion scavenger capturing platinum ions is preferably a planar mononuclear complex. The “planar mononuclear complex” is a planar complex in which one central metal (ion) is present in one complex. Moreover, the coordination number of the organometallic complex produced | generated when a platinum ion trapping agent capture | acquires platinum ion becomes like this. Preferably it is 2-4, More preferably, it is 2. Furthermore, the organometallic complex produced by the platinum ion scavenger capturing platinum ions is represented by the following chemical formula 1

It is preferable to have a coordination structure represented by The various forms of platinum ion scavengers described above are excellent in platinum ion scavenging ability, and organometallic complexes produced by capturing platinum ions can exhibit excellent performance as electrode catalysts.

  Specific examples of the preferred form of platinum ion scavenger include the following chemical formulas 2 to 9:

The compound shown by these is mentioned. However, it is not restricted only to these compounds, Of course, other compounds may be used as a platinum ion scavenger.

  The form in which the platinum ion scavenger is contained in the electrode catalyst layer is not particularly limited as long as it can capture platinum ions eluted from the catalyst active material containing platinum. Considering that the platinum ion scavenger that traps platinum ions functions as an electrode catalyst, the platinum ion scavenger should be contained in the electrode catalyst layer in the form supported on the “conductive carrier” described above. Is preferred. According to such a form, the platinum ion scavenger is supported on the conductive support, and thus the compound (for example, organometallic complex) generated by the platinum ion scavenger capturing platinum ions functions as an electrode catalyst. In this case, an electron conduction path is ensured, and excellent catalytic activity can be provided.

  As mentioned above, although the form using the compound which can produce | generate an organic platinum complex by trapping platinum ion was demonstrated in detail, platinum ion trapping agents other than such a form may be used. Examples of other platinum ion scavengers include multimerized porphyrins.

  The content ratio of the material constituting the electrode catalyst layer may be determined in consideration of the function as the electrode catalyst layer. In determining the content ratio of each material, it is preferable to consider the balance of the functions of each material. For example, in order to allow the electrode reaction to proceed sufficiently, it is necessary to ensure the amount of the conductive carrier that supports the catalyst active material. However, when the proton conductive polymer is insufficient, the conductivity of the generated protons is lowered, and the battery performance may be deteriorated. Moreover, when the platinum ion scavenger is insufficient, the capture of platinum ions eluted from the catalyst active material becomes insufficient, and the catalytic activity may be lowered.

  Preferably, the mass ratio X of the platinum ion scavenger to the mass of the catalyst active material (platinum ion scavenger mass / catalyst active material mass) is 0.25 ≦ X ≦ 0.7. More preferably, the mass ratio X is 0.4 ≦ X ≦ 0.6. When X is too small, there is a possibility that a sufficient platinum ion elution suppression effect cannot be obtained due to a lack of a platinum ion scavenger. Moreover, when X is too large, there is a possibility that the electron conduction resistance in the electrode catalyst layer is increased by an excess platinum ion scavenger, and sufficient battery performance cannot be obtained. By setting X in the above range, it is possible to effectively prevent elution of platinum ions while ensuring battery performance. However, the present invention can be carried out even outside the above range. The mass ratio X can be controlled by adjusting the raw material ratio when producing the electrode catalyst layer. When the platinum ion scavenger is contained in the electrode catalyst layer in a form supported on a conductive carrier, the mass of the conductive carrier carrying the platinum ion scavenger in calculating the above mass ratio X is It is not included in the “mass of platinum ion scavenger”.

  If necessary, the electrode catalyst layer of the present invention may contain other components in addition to the components described above.

  For example, the electrode catalyst layer of the present invention may further contain a water repellent material. By including the water-repellent material, discharge of water to the outside of the electrode catalyst layer is promoted, deterioration of the conductive carrier in the electrode catalyst layer is suppressed, and durability of the electrode catalyst layer can be improved. Examples of the water repellent material include a compound containing a fluorine atom. Specific examples of the water repellent material include polytetrafluoroethylene and carbon fluoride.

  The electrode catalyst layer of the present invention may contain dimethyl sulfoxide (DMSO) in addition to the water repellent material.

Since the electrode catalyst layer of the present invention contains a platinum ion scavenger capable of capturing platinum ions, the electrode catalyst layer of the present invention can prevent elution of platinum ions from the electrode catalyst layer as described above. Here, the effect by the electrode catalyst layer of this invention is demonstrated using FIG. FIG. 2 shows a ring using a rotating ring disk electrode (RRDE) device for the electrode catalyst layer of the present invention containing a platinum ion scavenger (graph A) and the electrode catalyst layer not containing a platinum ion scavenger (graph B). is a graph showing the results of the measurement of the current (I _r). In FIG. 2, the horizontal axis of the graph is the electric potential, and the vertical axis is the detected ring current (I _r ) [mA]. In this measurement, detection of the ring current (I _r ) means that platinum ions have permeated through the electrode catalyst layer.

As a result of the measurement of the ring current (I _r ), as shown in FIG. 2, the ring current (I _r ) was detected in the electrode catalyst layer (graph B) not containing the platinum ion scavenger. In contrast, no ring current (I _r ) was detected in the electrode catalyst layer (graph A) of the present invention containing a platinum ion scavenger. That is, platinum ion permeated the electrode catalyst layer (graph B) containing no platinum ion scavenger, but did not permeate the electrode catalyst layer (graph A) of the present invention containing the platinum ion scavenger. From this result, according to the electrode catalyst layer of the present invention, even if platinum ions are generated from platinum as a catalyst active material, the platinum ions are captured by the platinum ion scavenger contained in the electrode catalyst layer, It is suggested that elution to the outside of the electrode catalyst layer can be prevented.

  A second aspect of the present invention is a polymer electrolyte fuel cell in which the first electrocatalyst layer of the present invention is disposed on at least one of a cathode and an anode. As a configuration of the solid polymer fuel cell, as shown in FIG. 1, there is a structure in which the electrode catalyst layer 120, the gas diffusion layer 130, and the separator 200 are disposed on both sides of the polymer electrolyte membrane 110. However, it is of course possible to apply the first electrode catalyst layer of the present invention to a polymer electrolyte fuel cell having a configuration different from that shown in the drawing. In the present invention, the constituent materials other than the electrode catalyst layer are not particularly limited as long as the first electrode catalyst layer of the present invention is disposed on at least one of the cathode and the anode.

  However, as described above, the elution of platinum ions accompanying the repeated start and stop of the fuel cell is more remarkable at the cathode. Therefore, in the second polymer electrolyte fuel cell of the present invention, it is preferable that at least the cathode is the first electrode catalyst layer of the present invention. More preferably, the anode is also the first electrocatalyst layer of the present invention.

  A preferred embodiment of the polymer electrolyte fuel cell of the present invention is shown in FIG. In the polymer electrolyte fuel cell 10 shown in FIG. 3, a platinum ion trapping layer 150 is provided between the polymer electrolyte membrane 110 and the electrode catalyst layer 120 and between the gas diffusion layer 130 and the electrode catalyst layer 120. Intervene. Here, the platinum ion trapping layer 150 is a layer containing the platinum ion trapping agent described in the first aspect of the present invention. According to such a form, platinum ions that have not been captured by the electrode catalyst layer 120 are prevented from eluting to the solid polymer electrolyte membrane 110 side or the gas diffusion layer 130 side, and the decrease in catalytic activity is further suppressed. sell. In addition, the compound (for example, organometallic complex) produced | generated when the platinum ion trapping agent contained in the platinum ion trapping layer 150 captures platinum ions can also function as an electrode catalyst.

  The platinum ion trapping layer 150 includes a platinum ion trapping agent as described above. Since the preferable form of the platinum ion trapping agent contained in the platinum ion trapping layer 150 is as described in the column of the first electrode catalyst layer of the present invention, the description thereof is omitted here.

  Similar to the first electrode catalyst layer of the present invention, the platinum ion scavenger contained in the platinum ion trap layer 150 is also preferably contained in the platinum ion trap layer 150 in a form supported on a conductive carrier. According to such a form, the platinum ion scavenger captures platinum ions, thereby ensuring an electron conduction path when functioning as an electrode catalyst, and providing excellent catalytic activity.

  The base material constituting the platinum ion capturing layer 150 is not particularly limited as long as the platinum ion capturing agent can exhibit its function. However, preferably, the proton conductive polymer described in the column of the first electrode catalyst layer of the present invention can be used as the base material constituting the platinum ion capturing layer 150. According to such an embodiment, the platinum ion scavenger captures platinum ions, thereby ensuring a proton conduction path when functioning as an electrode catalyst and providing excellent catalytic activity.

  In the form shown in FIG. 3, the platinum ion trapping layer 150 is disposed on both sides of the electrode catalyst layer 120 in both the cathode and the anode. However, the present invention is not limited to such a form, and platinum ions are only present between the solid polymer electrolyte membrane 110 and the electrode catalyst layer 120 or between the gas diffusion layer 130 and the electrode catalyst layer 120. A configuration in which the acquisition layer 150 is disposed may also be adopted.

  Here, in the polymer electrolyte fuel cell, platinum ions from the catalyst active material contained in the electrode catalyst layer are likely to elute to the gas diffusion layer 130 side during rated operation of the fuel cell. Thus, it is known that elution to the solid polymer electrolyte membrane side is easy under the conditions of repeated operation and stoppage. Therefore, the arrangement form of the platinum ion trapping layer 150 can be determined by considering the desired operating conditions of the polymer electrolyte fuel cell 10 of the present invention.

  Then, the manufacturing method of the 1st electrode catalyst layer of this invention is demonstrated. In the following description, the platinum ion scavenger is supported on a conductive carrier and described as an example of the form contained in the electrode catalyst layer. However, the technical scope of the present invention is limited to the following form. It is not limited.

  The electrode catalyst layer of the present invention includes, for example, a step of preparing a liquid (liquid A) containing a platinum ion scavenger and a conductive carrier, a conductive carrier, a catalyst active material supported on the conductive carrier, and a proton. Preparing a liquid (liquid B) containing a conductive polymer, mixing the liquid A and the liquid B to prepare an electrode ink, applying the electrode ink, and volatilizing the solvent; And a step of forming a film containing the conductive carrier, a catalytic active material supported on the conductive carrier, the proton conductive polymer, and the platinum ion scavenger. Hereinafter, one embodiment of such a manufacturing method will be described in the order of steps. In addition, regarding the materials constituting the electrode catalyst layer such as the conductive carrier, the catalyst active material, the proton conductive polymer, and the platinum ion scavenger, the form described in the first of the present invention is used in the same manner. Description is omitted.

  First, a liquid (liquid A) containing a platinum ion scavenger and a conductive carrier is prepared. The liquid A is obtained by adding these materials to a solvent at a predetermined blending ratio and mixing them. Although it does not restrict | limit especially as a solvent, Preferably ethanol is used. Other solvents such as water or isopropyl alcohol may be used.

  On the other hand, a liquid (liquid B) containing a conductive carrier, a catalyst active material supported on the conductive carrier, and a proton conductive polymer is prepared. Similarly, the liquid B is obtained by adding these materials to the solvent at a predetermined mixing ratio and mixing them. The solvent of the liquid B is not particularly limited, but preferably ethanol or the like can be used. Of course, other solvents may be used.

  Next, the liquid A prepared above and the liquid B prepared similarly are mixed to prepare an electrode ink. The electrode ink is obtained by mixing the liquid A and the liquid B at a predetermined blending ratio.

  Further, by applying the electrode ink prepared above and volatilizing the solvent, it contains a conductive carrier, a catalytic active material supported on the conductive carrier, a proton conductive solid polymer, and a platinum ion scavenger. A film is formed. When applying the electrode ink, a known method can be used in the preparation of the electrode catalyst layer. For example, a screen printing method, a die coater method, a spray method, or the like is used. The application amount and application conditions of the electrode ink may be determined based on the knowledge already obtained, and are not particularly limited in the present invention.

  For example, the electrode ink is applied to both sides of the proton conductive polymer electrolyte membrane, and a laminate in which the electrode catalyst layer, the polymer electrolyte membrane, and the electrode catalyst layer are laminated in this order is obtained. A membrane electrode assembly is obtained by hot pressing the laminate and the gas diffusion substrate. However, the manufacturing method of the polymer electrolyte fuel cell is not limited to such a method, and other manufacturing methods may be adopted.

It is a schematic diagram which shows one Embodiment of the polymer electrolyte fuel cell of this invention. About the electrode catalyst layer (graph A) of this invention, and the electrode catalyst layer (graph B) which does not contain a platinum ion trapping agent, the result of measuring the ring current (I _r ) using a rotating ring disk electrode (RRDE) device is shown. It is a graph to show. 1 is a schematic view showing a preferred embodiment of a polymer electrolyte fuel cell of the present invention.

Explanation of symbols

10 polymer electrolyte fuel cell,
100 membrane electrode assembly,
110 solid polymer electrolyte membrane,
120 electrode catalyst layer,
130 gas diffusion layer,
140 carbon layers,
150 platinum ion trapping layer,
200 separator,
210 gas flow path,
300 Current collector.

Claims (10)

An electrode catalyst layer for a polymer electrolyte fuel cell comprising a conductive support, a catalytic active material containing platinum, and a proton conductive polymer supported on the conductive support,
An electrode catalyst layer for a polymer electrolyte fuel cell, further comprising a platinum ion scavenger capable of capturing platinum ions.   The electrode catalyst layer for a polymer electrolyte fuel cell according to claim 1, wherein the platinum ion scavenger is a compound capable of generating an organic platinum complex by capturing platinum ions.   The electrode catalyst layer for a polymer electrolyte fuel cell according to claim 2, wherein the organic platinum complex is a planar mononuclear complex.   The electrode catalyst layer for a polymer electrolyte fuel cell according to claim 2 or 3, wherein the coordination number of the organic platinum complex is 2 to 4. The organic platinum complex has the following chemical formula 1:

The electrode catalyst layer for a polymer electrolyte fuel cell according to any one of claims 2 to 4, which has a coordination structure represented by:   The electrode catalyst layer for a polymer electrolyte fuel cell according to any one of claims 1 to 5, wherein the platinum ion scavenger is contained in a form supported on a conductive carrier. Solid polymer electrolyte membrane;
A pair of electrocatalyst layers sandwiching the solid polymer electrolyte membrane; and
A solid polymer fuel cell having a pair of gas diffusion layers sandwiching a membrane-electrode assembly comprising the solid polymer electrolyte membrane and the pair of electrode catalyst layers,
A polymer electrolyte fuel cell, wherein at least one of the electrode catalyst layers is the electrode catalyst layer according to any one of claims 1 to 6.   The polymer electrolyte fuel cell according to claim 7, wherein the cathode is the electrode catalyst layer according to any one of claims 1 to 6.   A platinum ion capturing layer containing a platinum ion scavenger capable of capturing platinum ions is interposed between the solid polymer electrolyte membrane and the electrode catalyst layer or between the gas diffusion layer and the electrode catalyst layer. The polymer electrolyte fuel cell according to claim 7 or 8.   The solid polymer fuel according to claim 9, wherein the platinum ion scavenger is included in the platinum ion trap layer in a form supported on a conductive carrier, and the platinum ion trap layer further includes a proton conductive polymer. battery.

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